Epoxy resin compositions containing an epoxy resin and a curing agent as essential components are good in terms of physical properties such as high heat resistance, moisture resistance, and low viscosity and thus are widely used in a semiconductor sealing material, electronic components such as a printed circuit board, an electronic component field, conductive adhesives such as a conductive paste, other adhesives, matrixes for composite materials, coating materials, photoresist materials, color developing materials, etc.
Recently, in various applications, in particular, in applications to advanced materials, further improvement in properties such as heat resistance and resistance to moisture and solder has been required. For example, in the field of semiconductor sealing materials, surface mount packages such as a ball grid array (BGA) and a chip size package (CSP) have been developed and a reflow treatment temperature has been increased due to the use of lead-free solder. Consequently, electronic component-sealing resin materials having good resistance to moisture and solder have been further required.
Furthermore, recently, there has been an increasing trend in which halogen flame retardants are not used in view of environmental friendliness, and an epoxy resin and a phenolic resin (curing agent) that are halogen-free and that exhibit a high degree of flame retardancy have been desired.
As an example of a phenolic resin and epoxy resin for electronic component-sealing materials, the resins being capable of meeting such required properties, an epoxy resin or curing agent (phenolic resin) to which a benzyl ether structure is introduced by reacting a phenolic resin with a benzylating agent such as benzyl chloride under an alkaline condition has been disclosed (refer to, for example, PTL 1 and PTL 2).
However, although the epoxy resin and the phenolic resin described in PTL 1 or PTL 2 have improved flame retardancy, the flame retardancy does not reach the high level that has been recently required. In addition, the resistance of these resins to moisture and solder is also not sufficient.
Thus, epoxy resin compositions that combine a high degree of flame retardancy with high resistance to moisture and solder have not been obtained in the field of electronic component materials.